In a large mixing bowl, combine the drained crushed pineapple, drained mandarin oranges, mini marshmallows, shredded coconut, and chopped pecans or walnuts. Mix well to combine.
In a separate bowl, mix together the sour cream or Greek yogurt, granulated sugar, and vanilla extract until well blended.
Pour the sour cream or yogurt mixture over the fruit mixture and stir until everything is evenly coated.
Transfer the mixture into a 9×13 inch baking dish or a similar-sized container.
Cover the dish with plastic wrap or aluminum foil and place it in the freezer for at least 4 hours or overnight until completely frozen.
